Pixel dropout is a common issue within the printing industry. The dropout could result from a number of problems, for example a failed resistor element in the case of a thermal printhead or a blocked jet in the case of a multiple jet inkjet printhead. When pixel dropout occurs, it typically results in a vertical or horizontal line on the substrate being printed on, depending upon the printing direction since ink or dye is not being transferred from the failed print element to the substrate.
Substrates that are printed with pixel dropout are often considered defective and need to be disposed of, and are often remade which increases costs. Therefore, if pixel dropout does occur, it is best if the dropout is detected as soon as possible to minimize the number of defectively printed substrates.